From 1086 to 1114 the most powerful king in Ireland was Muirchertach O'Brien.
He had dealings with the Anglo-Normans and the Norwegian king, and dominated
most of the country. However, Domnaill Mac Lochlainn, king of the Ui Neill,
was able to hold him in check until the dynamic Turlough O'Connor, king
of Connacht (1106-1156) came onto the scene. Between 1115 and 1131, Turlough
destroyed the power of Munster and from 1140 threw his energies into making
himself king of Ireland. With his death in 1156, supreme power passed to the
king of the Ui Neill, Muirchertach Mac Lochlainn.

Mac Lochlainn allied himself with Dermot MacMurrough (Diarmait
Mac Murchadha), king of Leinster, against his main opponent, Rory O'Connor
(Ruaidhri O Conchobhair), king of Connacht. Mac Lochlainn held the upper
hand in Ireland until his death in 1166. O'Connor
along with his allies, particularly Tiernan O'Rourke, king of Breifne, as
well as the Dubliners, then drove MacMurrough from Ireland. MacMurrough
appealed for help to King Henry II of England and changed the course of
history by doing so. This opened the door for the Norman invasion of
Ireland beginning in 1169.

One area that is sometimes omitted in the history of Ireland includes the connections
between the Irish, Norse and Welsh prior to the arrival of the Normans of 1169. From the
11th century onwards political refugees from Britain gravitated toward Leinster in Ireland, and
who sought mercenary fleets from the Hiberno-Norse towns of Dublin, Waterford, and Wexford.
Some of these refugees included:

1039 - King Iago of Gwynned (Wales) was killed by the intruder Gruffydd ap Llewelyn and his family
took refuge in Dublin from where his son Cynan mounted two unsuccesful campaigns to regain the kingdom
of Gwynned. Cynan has a son, Gruffydd, born about 1054, whose mother was Ragnailt, daughter of Amlaib, son of
Sitric, king of Dublin. After a few unsuccessful attempts, Gruffydd (ap Cynan) sailed from Waterford to South Wales in 1081,
and with the help of Rhys ap Tewdwr, king of Deheubarth (Wales), he succeeded in restoring the title of king of Gwynedd to his
family (for a short period). In 1099 Gruffydd returned once more from Ireland in a successful attempt to regain Gwynedd which
he retained until his death in 1137.

1044 - Hywel ap Edwin, king of Deheubarth (Wales), was expelled by Gruffydd ap Llewelyn, and he sought refuge in
Ireland. He raised a fleet there and attempted to retake Deheubarth, but he and a large number of his Irish mercenaries were
slain in battle by Gruffydd.

1051 -Godwin, Earl of Essex, and his sons, formidable rivals of King Edward the Confessor,
were banished from England and sought the aid of Diarmait mac Máel na mBó, king of Uí Chennselaig
and of Leinster (1042-1072), who was grandfather of Diarmat Mac Murchada (above). The next
year they raised a fleet to launch attacks on the Devonshire, Somersetshire and Kentish coasts.

1055 - Aelfgar, earl of Anglia, son of Leofric, earl of Mercia, was banished for treason from England by Edward the Confessor. He went
to Ireland where he raised a fleet, formed an alliance with Gruffydd ap Llewelyn, king of Gwynedd, and led their
combined forces in an attack on the city of Hereford. As a result King Edward was obliged to restore him to the earldom of East
Anglia.

1066 - After the battle of Hastings in 1066, the sons of the slain King Harold, son of Earl Godwin, sought aid from
Diarmait mac Máel na mBó, and launched attacks on Britain over the next several years.

1088 - Rhys ap Tewdwr, king of Deheubarth (Wales), was expelled by Cadwgan, Madog, and Rhiryd, sons of Bleddyn, king of
Powys (Wales), and he fled to Ireland, raised a fleet in Dublin and returned to defeat them and retake his kingdom. Gruffydd, son of
Rhys ap Tewdwr, was fostered in Ireland, and it was from Ireland that he returned to Wales about 1113 in a bid to regain the
kingdom of Deheubarth. He managed to obtain a portion of Cantref Mawr (Wales) with the permission of King Henry I, but in 1127
he was obliged to seek temporary asylum in Ireland again.

1097 - Cadwgan ap Bleddyn, prince of Powys (Wales), fled to Ireland after the Norman victory of Mon in 1097. He returned in
1099 to reach an accommodation with the Normans. Cadwgan's son, Owain, was forced to flee to Ireland in 1109. On his return
from Ireland Owain mounted a number of plundering expeditions into Dyfed (Wales) and seized Norman captives, whom he shipped
as slaves to Ireland.

1102 - Arnulf de Montgomery, who had been granted the lordship of Pembroke (Wales) by King William Rufus about 1093, revolted
against Henry I in 1102. In consequence he sought a marriage alliance with Muirchertach Ua Briain, king of Munster (1086-1119) and
high-king of Ireland. Despite his Irish alliance Arnulf forfeited the lordship of Pembroke, and sought temporary haven in Ireland.

1144 - Gruffydd ap Cynan's sons, Cadwalladr and Owain, begin feuding in Wales. Cadwalladr treacherously killed Owain's nephew Anarawd of Deheubarth. Owain was incensed, and sent his son Hywel to invade Cadwalladr's territory. Cadwalladr sent to Ireland for help, resulting in a Norse fleet sailing to Abermenai, led by Þórkell, brother of King Ragnall of Dublin.

1165 - Henry II hired a fleet from Dublin in his Welsh campaign of 1165. The fleet can only have been made available to
Henry with the consent of Diarmait Mac Murchada as overlord of Dublin. The following year Diarmait was ousted from his
kingship in Ireland and sought aid from Henry II and the Cambro-Normans in Wales.